5 Shades of Tea – How Tea is Harvested and Processed

The process of turning leaves from an evergreen shrub into a tasty hot beverage has been refined over 1000s of years. The Chinese started drinking tea at least as early as 1122BC and will have undoubtedly started experimented with different harvesting and processing techniques very soon afterwards in order to make the perfect cuppa. Differing techniques, as you’re about to find out, having a huge affect on the final flavour of the beverage; growing the tea is only half the job!

Harvesting Tea

Tea destined for the speciality market needs to be handpicked to ensure its quality. It’s no good plunking each and every shoot; the leaves need to be carefully selected. Young leaves contain the most aromatics (or at least have them at the highest concentration) and so make the most flavoursome teas. However, if they’re picked too young, then the leaves are too small resulting in very little yield. Whilst there are many machines available they can’t harvest selectively, coupled with the fact that they struggle on uneven ground (many tea plantations are situated on slopes) meaning mechanised picking isn’t an option.

The harvesting of tea plants revolves around the terminal bud (sometimes referred to as the ‘tip’) found at the end of each stem. The bud is traditionally called the pekoe and there are three main picking styles:

  1. Imperial (P+1): With this style the picker removes the pekoe and leaf immediately below it. This fine style was historically reserved for visiting dignities, hence its name.
  2. Fine (P+2): This time the picker removes the pekoe and two leaves below it.
  3. Medium (P+3): Yes you’ve guessed it; the picker removes the pekoe and three leaves.

plucking tea leaves

There are other picking styles, including one which takes only the pekoe. However, this is only used for the production of a few teas, such as Yin Zen (Silver Needle).

Tea plants are evergreen so, weather permitting, harvests can continue all year round. In the tropics, plants can be plucked every 4-15 days. However, in some areas of the sub-tropics, or when tea is grown at very high altitudes, the plant becomes dormant for a few months of the year (usually when daily temperatures fail to reach 13C a tea plant won’t grow), leading to seasonality. For example, in Darjeeling, harvesting broadly runs as follows:

  • Winter (December – February) – plants lay dormant
  • Spring or 1st Flush (March – May)
  • Summer or 2nd Flush (June to July)
  • Autumn Flush (October to November)

Each harvest or flush tastes different from its predecessors.

Processing Teas

Tea comes in a variety of different colours or families: such as green, black, white, oolong and pu’er. However, all tea comes from the same plant, camellia sinensis. This is contrary to what early Westerners thought: China kept their tea production techniques a closely guarded secret and it wasn’t until a spy mission conducted by Robert Fortune in the mid 19th Century that it was discovered that green and black tea came from the same bush.

The different families of tea refer to how they’re processed, in particularly to what degree the tea leaves are allowed to oxidise. Oxidation refers to the chemical and physical changes with occur in the leaves during processing. It is sometimes referred to as fermentation although technically this is incorrect as no fermentation takes place, with the exception of pu’er (more on this later).

Oxidation is caused by an enzyme called oxidase which naturally occurs in the leaves. Once the cell walls of the leaves are broken they react with the oxidase, which starts altering the colour and flavour or the leaves. The pigmentation changes giving the leaves a darker appearance; while the catechins are convert into theaflavins and thearubigins (theaflavins lend tea briskness and brightness and thearubigins give depth and body). Oxidation only stops when heat is applied to the leaves to kill off the oxidase. As oxidation must take place shortly after harvesting, most plantations have their own processing plants.

Whilst processing techniques vary from country to country, and even between different areas within each country (the exact processes vary according to the variety of tea, the local climate and tradition of the area), the different families broadly follow the same processes.

different green tea processing techniques

Both these teas are green. However they both look quite different. The tea on the left from China, has been heated in a wok to kill the enzyme. Whereas the one on the right from Japan, has been steamed which preserves the green colour of the leaves.

Out of all the different families, green and white teas go through the least processing after harvesting. Both types of tea undergo minimal oxidation, which preserves their natural flavour, producing light, delicate and subtle teas.

When processing green teas; soon after plucking the leaves are heated in order to kill the enzyme that causes oxidation. They are then rolled and dried before being packed.

White teas on the other hand, are not heated. Once plucked, they are left to wither, sometimes in the open air, before being dried further, if need be, to stabilise the leaves (too higher water content will cause the leaves to rot) and packed.

Black teas get their flavour from a full oxidation process. Once harvested the leaves are withered, before being rolled to breakdown their cell walls and then are left to oxidise in a warm humid environment. Finally once the tea has fully oxidised it is allowed to dry.

Oolong or Wulong teas are semi-oxidized; somewhere between the minimal oxidation of green tea and the full oxidation of black tea. The process is very specialised. Broadly speaking it follows the same processes as black tea with one important difference, once the desired level of oxidation is achieve the leaves are fired, to stop the process, before being dried.

Some oolongs undergo only a light oxidation (10 to 30%) whereas others are more heavily oxidized (60 to 70%). As a result, oolongs vary greatly in flavour; with lightly oxidize teas having flowery and fresh notes, whilst more heavily ones have woody, fruity and caramelised notes.

There are two different types of Pu’er tea that involve slightly different processes. We have Sheng (raw) Pu’er which is fermented slowly over a very long period of time (10-50 years); and Shou (cooked or ripened) Pu’er which undergoes rapid fermentation. Both types of pu’er undergo the same initial processes: once picked the leaves are withered before being heated to stop oxidation and then dried. After this comes the fermentation stage. With the Shou method, the leaves are sprayed with water and covered, creating a warm and humid environment, and left to ferment for 1-2 months. With the Sheng method, the leaves are compressed, commonly into a cake shape; they are then wrapped and left to age. It’s during this aging process that the fermentation occurs.

tea processing chart - how to make the different families of tea

Click on image to enlarge

There is actually one more family of tea, Yellow teas, which are quite rare. They are similar to green and white teas in that they undergo, initially, minimal oxidation. However, yellow teas go through a slight post-oxidation, as they’re steamed under a damp cloth after withering, whilst the leaves are still warm.

Smoked, Scented and Flavoured Teas

Smoked, scented and flavoured teas aren’t counted as separate families. They simply take one of the existing families of tea, usually green or black, and add additional flavours or aromas. Smoked teas, like Lapsang Souchong, get their flavour from being dried over burning wood, typically spruce or pine. The word Souchong actually refers to the type of pluck used when harvesting leaves for these smoked teas, which takes the pekoe and four or five leaves below it.

Scented teas are made by mixing flowers or spices with the tea leaves. This is usually done at the drying stage, as the gentle heat that dries the leaves helps release the scent from the flowers or spices which the tea leaves readily absorb. Flavoured teas, like Earl Grey, are sprayed with essential oils from plants or fruits, or on lower quality teas with synthetic oils.

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